1. Field of the Invention
The present invention is in the technical field of methods of sample preparation and manipulation for preparing a specimen for transmission electron microscopy (TEM) examination. More particularly, the present invention is in the technical field of sample preparation and manipulation by methods of in-situ lift-out techniques.
2. Description of Related Art
The standard in-situ lift-out method involves moving a micromanipulator probe to a sample membrane that was previously milled from a wafer by use of a focused ion beam/scanning electron microscope (FIB/SEM) or similar machine. This leaves the sample membrane approximately 1-2 microns thick with varying length and height (typically 5-15 micron length and 5-15 micron height). The micromanipulator probe is then welded to the sample membrane by ion beam assisted metal deposition. When the weld is secured, the sample membrane is then cut from the wafer by a focused ion beam (FIB) and extracted from the wafer.
The probe then moves the sample to a transmission electron microscope (TEM) grid where it is welded to the TEM grid by ion beam assisted metal deposition. When the sample membrane is secured to the TEM grid, the probe is cut from the sample by FIB. The sample membrane is then milled again by FIB until it is thin enough for use in a TEM, typically between 50-200 nanometers thick. The entire method is done within the FIB/SEM machine chamber while it is activated and under vacuum.
The current method of in-situ lift-out has a low productivity, as the number of samples that are produced is relatively low in comparison to the total amount of time and effort that is used for this purpose. Features that shorten the time of preparing a sample and/or increase user productivity are highly desirable in this field.
The current method also has problems in metal deposition steps where excess material may sputter on, and contaminate unintended objects.